Conventional wheelchairs normally include left and right seat supports in the form of frame tubes together with centrally pivoted cross bracing extending between the upper left seat support and lower right side of the wheelchair frame and the upper right seat support and the lower left side of the wheelchair frame. With this arrangement, the centrally pivoted cross bracing can scissor together upon movement of the seat supports and side frames towards each other to fold the wheelchair, the seat itself generally comprising a flexible canvas material which will simply fold.
The left and right seat support frame tubes themselves are secured to the upper ends of front post slide members usually in the form of tubes arranged to be received in front posts mounted to the lower frame of the wheelchair. The action of scissoring together the cross frame to fold the wheelchair necessarily raises the height of the seat supports and the supporting front post slides will rise a corresponding vertical distance. However, these slides will not separate from the front posts themselves because they are designed of sufficient length to remain in sliding or telescopic relationship with the front posts.
In the case of a wide seat wheelchair which is often required for relatively portly paraplegics, a complete redesign of the wheelchair frame and other cooperating components is usually necessary. Providing a wider seat at the same level above the ground when the chair is in its normal condition for use requires relatively longer cross bracing. When this cross bracing is scissored to fold the wheelchair, because of the increased length and width of the seat, the seat supports will be raised to a greater vertical level than is the case when a normal seat and normal cross bracing is used. The respective lengths of the front post slides and front posts themselves are normally not sufficient to accommodate this increased vertical movement and as a result, without redesign of the same separation would occur, the front post slides simply being pulled upwardly completely out of the front posts. It will thus be appreciated that almost the entire frame structure of the wheelchair requires major modification in order to provide a wide seat wheelchair.
It would be highly desirable if conventional wheelchairs could be converted to a wide seat wheelchair without necessitating any major redesign or modification of principal components of the wheelchair. Not only would the expense of having to redesign an entire wheelchair be avoided, but if the modifications could be made sufficiently simple, they could be carried out in the field and thus avoid the problem of returning the wheelchair to a factory for modification.